Not to nitpick, but dedup isn't really compression in one significant respect. e.g. you can have 3 copies of the same data chunk and it is only stored as one (effectively a compression ratio of 4:1), even if the data in question is uncompressible (due to already being compressed.)
-----Original Message----- From: Edward Ned Harvey [mailto:[email protected]] Sent: Wednesday, November 02, 2011 9:36 AM To: [email protected] Subject: Re: [OpenIndiana-discuss] Fwd: poor zfs compression ratio > From: Krishna PMV [mailto:[email protected]] > > Resending as my previous email didn`t get through the list. Can someone > please advice how we can improve compression ratio here? Thanks! Nothing you can do, except store the mail in compressed files like xz or whatever. All general-purpose compression algorithms rely on one basic principle: Reducing or remapping repeated data patterns. If you're getting weak compression ratios, it means your data is already compressed, or not massively repeated. Either way, you're already doing the best you can do. Note: Dedup is in fact a compression algorithm, but it's being applied pool-wide instead of at the block level, so it deserves a different name. We call it dedup instead of compression. _______________________________________________ OpenIndiana-discuss mailing list [email protected] http://openindiana.org/mailman/listinfo/openindiana-discuss _______________________________________________ OpenIndiana-discuss mailing list [email protected] http://openindiana.org/mailman/listinfo/openindiana-discuss
